Iron Buffer System in the Water Column and Partitioning in the Sediments of the Naturally Acidic Lake Caviahue, Neuquén, Argentina

CABRERA, JM; DIAZ, MM; SCHULTZ, SS; TEMPORETTI, PF; PEDROZO, FL

JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 318 p. 19 - 26

0377-0273

p { margin-bottom: 0.25cm; direction: ltr; color: rgb(0, 0, 0); line-height: 120%; }p.western { font-family: "Liberation Serif","Times New Roman",sans-serif; font-size: 12pt; }p.cjk { font-family: "Droid Sans Fallback","Times New Roman"; font-size: 12pt; }p.ctl { font-family: "FreeSans","Times New Roman"; font-size: 12pt; }Sedimentary iron partitioning wasstudied for five sediment strata (16 cm depth) at three samplingsites of the naturally?occurring acidic Lake Caviahue (Patagonia,Argentina). Additionally, water column iron was modeled based onfive?year period input loadings to study a possible iron buffersystem. The partition coefficient between the water column and thetotal iron content of the sediments was also addressed. Sedimentaryiron was found to be distributed, on average, in the following forms:exchangeable (6%), iron oxides (4%), pyrite and reactive organicmatter (38%) and residual (non?andesitic) materials with a highcontent of humic acids (52%). Furthermore, we found that thedissolved iron in the lake was nearly constant throughout the fiveyear period we studied. This isconsistent with the existence of an iron buffer system in the lake atpH between 2.0 to 3.0, which may cause differential ironprecipitation at the delta of the volcanic river with respect to thedeeper northern and southern arms. Sedimentary iron measurementstaken at the delta further support the existence of a buffer system,where it was found that the iron content in the sub-superficialstratum (2 cm) was double that of the remainder of the verticalprofile at the same site.